1. Field of the Invention
The present invention relates to insertion/extraction mechanisms for avionics electronic chassis and more specifically to a mechanism which accommodates a large number of electrical connectors and inherently prevents damage to any misaligned connectors and/or the pins thereof. The mechanism further provides a compact longitudinal profile adapting it to use in restricted spaces and, in addition, provides a carrying handle to facilitate portability of the chassis.
2. Description of the Prior Art
As is well known to those skilled in the avionics packaging and installation art, the electronics chassis or electronics box must be capable of being routinely installed and removed for maintenance and/or replacement purposes. Usually, each chassis is mounted on and secured to a tray which in turn is permanently secured to a shelf in the electronics bay or bays of the aircraft. The tray includes at its rear one or more electrical connectors each including a plurality of circuit pin sockets or pins which in turn are connected with the permanent aircraft wiring harnesses. The chassis includes at its rear corresponding electrical connectors and circuit pins or sockets which mate with the tray connectors to electrically interface the chassis circuits with the aircraft wiring. The chassis and tray are rigidly joined together by some form of insertion, extraction and/or holddown devices.
A number of such devices have been devised in the past and a number of these are presently in general use. One of the most common designs involves a pin/hook/elongated camming lever arrangement (FIG. 1) while another involves a simple lug/screw/wing or knurled nut arrangement (FIG. 2). Two disadvantages are readily apparent in the FIG. 1 prior art arrangement; first, there is no insertion force protection, that is, if the electrical connectors are misaligned and the open levers (usually one on each side of the box) are raised a large closing force applied by the installer may damage the connector and/or its pin; second, the elongated levers in open position greatly increase the overall longitudinal profile of the box thereby requiring a large space in the aircraft electronics bay to effect box installation and removal. Additionally, the box handles prevent the use of extended box volume above the holddown mechanism. It should also be noted that the forces required for the disconnection of the electrical connectors upon extraction of the box from the tray is completely uncontrolled, thereby subjecting the connectors to possible damage upon removal.
The prior art arrangement of FIG. 2 is simply a holddown device with no connector protection and no control or limitation of the longitudinal insertion or extraction forces. As in prior art mechanism of FIG. 1, extraction of the chassis is uncontrolled and may require a manual "wiggling" of the chassis back and forth and up and down to disconnect the electrical connectors which may cause connector and/or pin damage.